Background: Pyloromyotomy is one of the most common surgical procedures performed on otherwise healthy infants. Pyloric stenosis results in a hypochloremic, hypokalemic metabolic alkalosis that is considered a medical emergency. This alkalotic state is believed to be associated with an increased incidence of apneic episodes. Because apnea tends to occur during anesthetic emergence, we sought to examine the association between the preoperative serum bicarbonate level and anesthetic emergence time after laparoscopic pyloromyotomy.
Methods: Data were collected from patients who underwent laparoscopic pyloromyotomies from April 2014 to October 2018. To estimate the correlation between preoperative bicarbonate level and emergence time while accounting for the positive skew of emergence time and potential confounding variables, a weighted quantile mixed regression was used. Due to a nonlinear association with emergence time, preoperative serum bicarbonate was split into 2 continuous intervals (<24 and ≥24 mEq/L) and the slope versus outcome was fit for each interval.
Results: A total of 529 patients who underwent laparoscopic pyloromyotomy were analyzed in this study. After controlling for confounders, the preoperative serum bicarbonate interval of ≥24 mEq/L was linearly associated with median emergence time (median increase of 0.81 minutes per 1 mEq/L increase of bicarbonate; 95% confidence interval [CI], 0.42-1.20; P < .001). Only 3 patients (0.6%) had apneic episodes after pyloromyotomy despite all having preoperative serum bicarbonate levels <29 mEq/L.
Conclusions: Preoperative serum bicarbonate was positively associated with median anesthetic emergence time in a linear manner for values ≥24 mEq/L, although this correlation may not appear to be clinically substantial per 1 mEq/L unit. However, when preoperative serum bicarbonate levels were dichotomized at a commonly used presurgical threshold, the difference in median emergence time between ≥30 and <30 mEq/L was an estimated 5.4 minutes (95% CI, 3.1-7.8 minutes; P < .001).